First, pour ketchup into your cup or dish. Now, set your timer for 2 full minutes. But the rarest of all is this single known example from the Denver mint. It is the most valuable penny in the world. There are probably 25 to 35 Philadelphia Mint steel cents from in existence. Just two San Francisco Mint steels are known. Even though the United States Mint switched pennies from a steel composition to copper in , some steel planchets were left behind in the presses, presumably by accident.
A pH of less than 7, which is neutral, is critical. A range between 3 and 5 is good. Tomato juice has a pH of around 4. The other element that is important for a good penny cleaner is the presence of ions of hydrogen and chlorine. These ions allow the acid in the chosen cleaner to react with the copper oxide of the tarnish. Acids such as citric acid, acetic acid and hydrochloric acid dissolve the copper oxide, breaking apart its molecules and forming molecules of water and stable copper compounds, which are dissolved in the cleaner.
This process removes a microscopically thin layer from the surface of the penny, leaving behind the shiny copper surface. Middle Men While they won't work as well as lemon and lime juice, other juices contain a moderate amount of citric acid. Just Don't Have It Juices that won't work are those considered alkaline.
How to Clean Your Pennies When you are cleaning your pennies, use highly concentrated or freshly squeezed juices. Put the pennies in the container. Add the juice. Pickle or lemon juice works best. Let the pennies sit. The time will vary based on the oxidation and the number of pennies. This could take a few hours to days. If you have a lot of pennies, shake the jar a few times a day to make sure the juice covers all of them. After all the copper oxide is gone, use a strainer to drain the juice.
However, don't throw away your juice in case some still need it. Rinse with cool water. If any pennies still have oxidation, put them back in the juice. How to Test Since it's always more fun to find out firsthand than to read an article, why not conduct an experiment?
Once the materials are ready, follow these steps: Pour each juice into a mason jar and label it with tape. Dip a piece of pH paper into each jar. The bluer it turns, the more alkaline the juice. The redder it turns, the more acidic.
Set the papers aside to dry and label each. Drop two pennies into each jar and seal it tightly. Let the pennies sit in their respective juices overnight. Refrigerating the jars is optional. Check the results the next day and compare them to each juice's pH. Rank the appearance of each penny from one to five and see how it corresponds to acidity. Cleaning Pennies While this experiment is a good way to teach kids about chemistry, it is not a good way to clean pennies that are collector's items.
Penny Cleaning Science Project. By Mary Gormandy White.
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